Fluid pressure vehicle braking system



April 13, 1954 L. TROY FLUID PRESSURE, VEHICLE BRAKING SYSTEM 4Sheets-Sheet Il.

Filed Oct. 24, 1950 Ail...

, INVEN TOR. L Ear/MD no Y BY 1. s. @www Y AQ April 13, 1954 TROY2,675,099

i FLUID PRESSURE, VEHICLE: BRAKING'SYSTEM Filed oct. 24. 195o 4sheets-sheet 2 IN V EN TOR.

April 13, 1954 Filed Oct. 24. 1950 L.. TROY 2,675,099

FLUID PRESSURE, VEHICLE BRAKING SYSTEM 4 Sheets-Sheet 5 POLI) HOTINVENTOR. 5o/mm may April, 13, 1.954 TROY FLUID PRESSURE, VEHICLEBRAKING SYSTEM i Sheets-Sheet 4 Filed Oct. 24, 1950 VMJEHII mgm..

Patented Apr. 13, 1954 UNITED STAT iiisiTENT OFFICE FLUID PRESSUREvEnroLii eaAKINc SYSTEM Leonard Troy, Clarks Summit, Pa.

Application 'October 2a, 1959, Serial No. 191,767

1 Claim. 1

This invention relates to improvements in brake systems and brakeoperatingr elements such as are employed in the operation of motorvehicles. The objects of the invention are to provide new and improvedbrake actuating and operating instrumentalities, units or valvemechanisms which may be combined in order to provide a safer, speedierand more efficient brake system in which a minimum of initial energy isutilized for maximum braking eiiiciency. Another object ci the inventionis to provide cylinder and valve units which may be incorporated inexisting brake sys tems without requiring major changes in con*vstruction and arrangements c-f such systems and without requiring moreskill in operation of the improved system than that which is nowrequired vfrom a skilled driver of an automobile truck,

trailer or other motor vehicle.

The invention is disclosed in connection with the operation of acombined tractor and trailer, not because all the features of theinvention are limited to such use, but because the novel iea- .tures ofthe invention can best be understood and explained when described andillustrated in connection with` such a complete embodiment. Theinvention may be used in the operation of a tractor alone or in theoperation of an automobile truck. Some of the features may be used inautomotive systems vother than that described, claimed `and illustratedin the following specification and accompanying drawings in which Fig. 1is a diagram illustrating a complete braking system embodying theinvention as applied in the operation of a combined tractor and trailer.

Fig. 2 is a sectional View of a master cylinder Which is part of thebraking system and which the master cylinder and the brake cylinder of awheel brake.

Figs. 5, 6, '7 and 8 are sectional views of different forms of pneumaticbrake valves which are used in the braking system between the mastercylinder and the brake cylinders of a trailer, for example.

Fig. 9 is a sectional view of a temperature control valve which may beused to control the temperatures in the automotive system according tothis invention, or which may be used in non-auto- `motive systems.

It is included as an adaptation of the principle underlyingtheiconstruction` and operation of the pneumatic brake valves.

Referring first to Fig. 1, an automobile tractor or auto truck isdiagrammatically identified for the purposes of this disclosure by thevehicle motor it, the drivers seat Il, the front wheel I 2 and the rearWheel I3. Only the wheels on one side of the tractor are shown, thesystem being the same for both sides. The foot brake pedal is shown atlil and the master cylinder at 5. Each wheel has the usual brake it withbrake cylinder il, conventionally illustrated.

The master cylinders-The valve mechanism is enclosed within a cylindercasing i5 provided with partitions I8 which divide the interior into alarge pressure chamber IS and a smaller pressure chamber 2b with anoutlet chamber at 2 l. A luid reservoir 22 is formed apart from thechambers with an inlet at 23 for iilling in duid indicated at 24. Thereservoir communicates with the chambers I9 and 2i) through ports 25 and2li, respectively. A single piston 2l is mounted to reciprocate withinthe two pressure chambers. The piston has a large head Ztl and a smallerhead 29 to lit the chambers.` The larger piston head 23 has a feed backpassage t which communicates with the reservoir through a port 3i. Acheck valve 32 in the smaller piston head i5 controls the passage ofnuid between the two chambers I9 and 2t. Another check valve 33 controlsthe'passage oi uuid between the two chambers i9 and 22. The piston 2l isprovided with a relief valve 34 which normally closes a port t5 underpressure of a spring St which acts upon the valve stem 3i. The end ofthe stem is open to pressure in the chamber 2&3 as shown.

The outlet chamber 2| carries a double` acting air valve 33 whichoperates automatically to prevent air from entering the master cylinderthrough a port 39 from leaks in the braking system. Such pre-setautomatic air valves are known and used in the art, so a detaileddescription thereof is deemed not necessary. The outlet chamber 2i alsocontains a plurality of surge valves 40. There is one such valve foreach wheel brake cylinder. Only two are shown. Ii there is a leak in thesystem between the master cylinder and the brake cylinders, a suddensurge of iluid to the leaking part will force thc valve piston lllupwards against a seat 32 thereby shutting oi the supply of fluid to theleak while pressure will be maintained in the non-leaking brakes. Whenthe leal; has been repaired the piston il returns automatically tonormal position.

lopen port 35, passage 30 and port 3l.

-tion by a spring 53.

The operation of the master cylinder is as follows: When it is desiredto apply the brakes to the wheels, the driver steps on the brake pedalI4 which is connected by a linkage ftd to the master cylinder piston 21and the latter moves forward, pressure thereby being built up in thechambers I9 and 25. The initial pressure is conveyed to the brakecylinders through the outlet chamber 2l and the pipe lines 55, Fig. 1,to apply good braking contact between the braking surfaces. At apredetermined brake pressure the relief valve 35 opens, the pressure inthe chambers i9 and 25 having been equalized through the opening of thecheck valve 32. The ports 25 and 25 are now closed by the forwardmovement of the piston.

The pressure in the chamber i acts directly rearwardly upon the valvehead 3.41. The pressure in the chamber likewise acts upon the end of thevalve stem 31. The fluid in chamber IS now ows back into the reservoirthrough the With the drop of pressure in the chamber I9, the reliefvalve 32 closes so that the pressure in the chamber I9 is completely cutoff from the braking system. Since the piston pressure area in chamber2D is much less than the total pressure areas of the two piston heads, asmall increment of force applied to move the piston will produce a muchlarger increment of pressure than when both pressure chambers and bothpiston pressure areas are utilized. As the pressure in the smallerchamber 2E increases by further forward movement of the piston, more andmore of the total force necessary to open the relief valve 34 will beexerted thereon until the pressure in the chamber i9 approaches zero andwhereby the entire force applied on the brake pedal is utilized to applythe brakes.

When the pressure on the foot pedal is released, the piston 21 willreturn to its initial posi- Relief valve 35 will close the port 35 bythe spring 35. Ports 25, 26 and 3l will open to equalize the pressureand the check valve 33 will open so that pressure huid may flow backinto chamber i9.

The advantage of the master cylinder is that a large volume of uid isinitially utilized to start braking at the instant depression of thebrake pedal and thereafter only a small increment in applied force isnecessary to produce a very large braking pressure. The use of surgevalves in the system insures that the flow of pressure fluid to leakingpoints will be instantly stopped while the other brake lines remainoperable.

Self adjusting brake 'valve-For each brake cylinder in the system a selfadjusting brake valve 50 is employed to permit unlimited ow of pressurefluid from the master cylinder to the brake cylinder I1 and permit onlya predetermined quantity of fluid to pass back to the master cylinderthereby compensating for wear on braking surfaces and keeping them inclose proximity or full adjustment. The self adjusting brake valvereceives operating iuid from the master cylinder through the aforesaidpipe lines 45 and is in turn connected to the brake cylinder by a pipeline 5i, Fig. l.

Fig. 3 is a sectional view of one embodiment of a self adjusting brakevalve according to. this invention. The valve housing 50 contains avalve chamber 52. The valve housing has a bypass 53 and two piston stops54 and 55. A piston 56 with a passage 51 is mounted to slide in thechamber 52. When the master cylinder is operated as described above,pressure fluid enters the valve chamber 52 through the pipe line 45. Thepiston 56 then rises in the Valve chamber and the pressure upon the uidin front of the piston will normally be suflicient for braking purposes.If however, the brakes do not respond to such pressure because of pooradjustment or for other reasons, the piston 55 will continue to rise andmove past the port 59. More fluid will then iiow from the mastercylinder to the brake cylinder l1 by way of passages 51 and 53, theadded pres-- sure compensating for whatever irregularity may exist inthe performance of the braking surfaces. When the pressure is released,the piston 55 will return and be seated on the stop 54 thereby sealingthe uid in the restricted space in front of the piston and maintainingthe braking surfaces in close proximity ready to respond to the nextbraking operation. The upper stop 55 limits the forward movement of thepiston 55.

Another embodiment of the self adjusting brake valve is illustrated inFig. 4. The valve housing 66 forms a chamber 6I containing braking fluidand is provided with a plate valve 62 to which bellows 53 is attached,the lower edge of the bellows being secured to a nange 54 which supportsupstanding stops 65 upon which the plate valve rests. The valve has acheck valve 61 with a spring attached to a support 58 on the platevalve. The latter has a port Se controlled by the check valve.Projections 15, 1G are upper stops for the plate valve.

In operation, when fluid from the master cylinder I5 enters the valvechamber 5l through the pipe line d5, the pressure will cause the platevalve to rise until it strikes the stops 10. If now the brakes are inproper adjustment, the increase in pressure above the plate valve willsuffice for braking pressure which is increased by the expansion of thebellows 63. If however, the brakes do not respond properly to thepressure thus far applied, continued pressure from the master cylinderwill cause the check valve 61 to open and additional fluid will thenpass through the port 5e to the brake cylinder via connection 5l. Whenthe pressure stops increasing, the check valve 51 will close and whenthe pressure is released the bellows G3 will collapse-and the platevalve then returns to the stops 55, there being then suflicientclearance between the braking surfaces to compensate for wear andmaintain the brakes in good adjustment.

The braking system and units explained in the foregoing provide meansfor applying the tractor brakes. The entire disclosure includes,however, means for also applying the trailer brakes and to accomplishthis object certain other elements are incorporated in the system. Suchother elements are herein called pneumatic brake valves and areillustrated in Figs. 5-8.

For a better understanding of the operation and function or" thepneumatic brake valve units it may be noted that there are two basictypes of vacuum brake systems known in the art. One type is known as thebrakes in air suspended system characterized by the air in the controllines beingevacuated in order to applyV the brakes. The other type isknown as air suspended vacuum operated brakes characterized by vacuumbeing normally maintained in the control lines, but is reduced oreliminated upon application of the brakes. If the trailer brake systemis that of air suspended vacuum operated brakes, the brakes are appliedby exhausting the air in the brake control lines whereby to apply thebrakes. One embodiment` `of `a pneumatic brake valve for this purpose isillustrated in Fig. 5. See also Fig. 1 in which the trailer is indicatedas having wheels ll, ll, only one side being shown. In explaining thefunction of the pneumatic brake valves according to this invention, thebrakes themselves are not shown, nor their construction explainedbecause it is known in the art how such brakes are manufactured andoperated when vacuum is utilized to apply the brakes.

The pneumatic brake calves-The valve, Fie. 5, consists oi a valve casing'l5 having a valve chamber 'It which is connected by a pipe line Tl to apneumatic relay valve '18, Fig. l, or to the trailer brakes direct. Thevalve chamber "it has an air inlet at 'is and a vacuum suction outlet at80 connected to a vacuum tank 8l operated in known manner from the motorlil, Fig. l. A check valve E2 controls the passage from the motor to thetank.

In the valve i5 a diaphragm 33 is stretched across the chamber lt andabove the diaphragm there is an air port 84'. 'The chamber contains twoplate valves. The lower valve closes against a valve seat E6 and isconnected by bellows 81 to a supporting iiange Sii. The valve 85controls the passage of air from the inlet 'i9 to the chamber 76. Asecond plate valve 83 closes against a seat 89 and is provided withbellows @il connected to another fla-nge El! as shown. 'Ihe valve 88controls the of from the chamber it out through the suction outlet 80.The diaphragm 83 carries a valve stern 32 having arms 93, 94 for openingthe valves til, 85, respectively. The valve stein, see Fig. l, may bemanually operated by a hand lever di?, or it may be operated from themaster cylinder through a hydraulic relay 91 which is connected to themaster cylinder outlet chamber 2i by a connection 98 similar to theconnection i5 shown in Fig. 2.

The relay dl has a pressure actua-ted piston 99 adapted to engage thehand lever Sii for operation (lifting) of the valve stem 92 in the valve15, Fig. 5.

The operation is as follows: When the driver operates the hand lever etor whenV he steps on the foot pedal lli to apply the trailer brakes, thevalve stern 92 is lifted in the valve chamber i6 and the arm 93 opensthe plate valve 88 so that air in the chamber lil, above and below theValve 88, and in the trailer brake system, via connection ll, isexhausted through the vacuum outlet 80 until the forces of suction belowthe diaphragrn 33 balance the lifting force applied' to the valve stern92. As this lifting brake applying force is reduced by gradual releaseof the foot pedal so that it is less than the suction below thediaphragm, the latter will be drawn inward and the upper plate valve di?will close. At the same time the arm Sift on the stern 92 will move thelower valve S5 down troni its seat lit and thereby open communicationbetween chamber it and the air port le. Atmospheric air will then dowinto the chamber. The diaphragm 83 will be moved back into initial4position and the valve mechanism will again be balanced, the two platevalves being closed by expansion ci the bellows which also serve toprevent leakage from the chamber 'i6 to the connections 'i9 and 813. A.spring itil may be used to assist in closingthe valves.

Frein this it will be seen, that when the brakes are to be applied, theair in the brake control lines is evacuated by suction (vacuum). Whenthe pressure on the brakepedalis reduced, vacuum is cut. oil from thebrake lines and airv enters the saine to balance the system for the nextoperation. The operation and function of the pneumatic brake valve asshown in Fig. 5 therefore meets the definition of an air suspendedvacuum operated brake system explained above.

The valve shown in Fig. 5 may also be used for applying brakes in whatis known as the air system. In such a system the actuating force appliedto the valve stem 92 is reversed. The valve stem is being depressedinstead of being lifted. This may be done, for example, by rearrangingthe hand lever 98 and the hydraulic relay 97 to depress the stein 92instead of lifting it. Such re-arrangeinent is not shown it beingobvious from the illustration in Fig.' 1.

The operation of the valve in Fig. 5i when it is used in air systems iseasily understood from the foregoing description of the valve. With thechange in direction of movement of the valve stein 32 the valve operatedas follows:

Air pressure is supplied through the inlet 'I9 and the connection isopen to the atmosphere. When the brakes are to applied, the valve stem92 is moved down (not up) in the chamber it to open the valve 35 so thatair under pressure may be admitted to chamber i5 through the inlet 'i9and through connection 'Il to the trailer brake system to apply thebrakes. When the air pressure in chamber le from inlet against thediaphragm 83 is suicient to balance the downward force exerted upon thevalve stem 92, the diaphragm lifts he stern so that the valve 85 willagain close and the system will again be in equilibrium. If the downwardpressure on the stem 92 is reduced, the air pressure below the diaphragmwill tend to move the valve stem upwards thereby opening the other valve88 and permit some air to escape into the atmosphere via connection 8Guntil the system is again balanced.

Fig. 6 illustrates a modiiication in which pneumatic, or hydraulicpressure, or vacuum may be applied through an inlet iiiZ to the chamberlLi above the diaphragm S3 for operating the valve instead of using aforce applied directly to the valve stein by the hand lever or hydraulicrelay ill as explained above.

Another modification of a pneumatic brake valve is shown in Fig. 7 foruse in an air suspended vacuum operated brake system which is uso-d ontractor trailer combinations in which vacuum is maintained in the brakecontrol lines at all times except when the vacuum is either reduced orcompletely released. In this modification a spring itil is provided topush the valve stein 92 upwards so as to keep the upper plate valve Seopen. Compare 5. The valve chamber i6 and gthe trailer brake system willthen be normally under a vacuum from the connection 8i). The force ofthe spring l is such that it balances the suction force below thediaphragrn S3 and vacuum is maintained in the brake control lines.

When the brakes are to be applied, the valve stem 92 is depressed by thesame-reversed mechanism` caplained above, Fig. l, so that the uppervalve 38 is closed against the force of the spring, thereby opening thelower valve ii to admit air through the inlet l@ to reduce or eliminatethe vacuum in valve chamber "iii and in the control lines via theconnection ll. The outside force to depress the valve stem 921. is againbalanced by the reduced suction below the diaphragm 83 and the force ofthe spring IBB so that valve 88 is again opened and the chamber 'I6becomes open to suction from the connection at 50.

If the downward actuating force on the valve stem is reduced orwithdrawn, the spring |06 will again open the upper valve S3 and therebyagain open the chamber 'l5 and the brake lines to vacuum applied throughthe line 85.

The operating principle of the pneumatic brake Valve described may beapplied to a brake valve in a system of the air suspended vacuumoperated brake type where the valve then may be used as a high speedrelay valve with provision for automatic release of the brakes, forexample, when the valve is used as a relay valve on a trailer tractorcombination. Such a type oi valve is shown in Fig. 8 to which referenceis now made. Pneumatic relay calca-The mechanism is contained within avalve casing "8, Figs. l and 8, having an upper diaphragm H forming asuction chamber ||l| to which vacuum is applied from the pneumatic brakeValve l5, Figs. l and 5, through a suction pipe Vi which enters thevalve 18 at the top as shown. Below the diaphragm ,Ill there is a secondsmaller diaphragm H8. vBoth diaphragms carry the valve stem H9 havingarms 93 and 94 for operating plate valves ,58 and 55 which have bellows95, 8l, the arrangement being the same as shown in Fig. 5. The lowerbellows 8l are secured tc a partition |25. Below the latter is a thirddiaphragm |22 forming a chamber |23 which is connected to the tractorvacuum line y| lf3 by a pipe line |25, see Fig. l. One or more push rods|25 are slidably carried in the Valve casing i8. The push rod rests uponthe lowermost diaphragm |22 and at the top the rod engages the diaphragmlll.

The space between the two upper diaphragme forms an air chamber |25 withan air port |2l. The space between the diaphragm H8 and the `partition|25 forms a brake chamber which is connected to the trailer brakes byconnection |35. Vacuum is supplied to this chamber through vacuum pipeH2 whereby the Valve i8 is con nected with a trailer vacuum ,tank ||3which in turn is connected to the tractor Vacuum tank 8| by a pipe lineH4, see Fig. 1. Below the lower plate Valve 55 there is an air inlet at|40. The

space above the lowermost diaphragm |22 forms another air chamber |25with an air port |23. A spring |38 acts against the diaphragm |22.

Each trailer wheel, Fig. l, has a brake member |3| operated by .asuitable linkage |32 ccnnected to a diaphragm |33 within a casingformtwo separate chambers 35 and |34. The chamber |34 is connected withthe valve l@ by the aforesaid pipe line |35.

The operation of the relayvalve 18 is as follows: rEhe trailer brakes llare normally suspended in air by the diaphragms |53 in chambers `|35 and|356. 1f now the connection IM should break, the Vacuum in the lowermostvalve chamber i23-which vacuum is supplied to the chamber via the pipeconnection |24 from the tractor vacuum tank ill-will be lost. The spring|35 will then exert its force upwards against the diaphragm |22 and bymeans of the push rod |25 cause the upper diaphragm to be lifted. rThismovement is in turn transferred to the valve stem IIS and the arm 93will open 'the` upper plate valve 88. Vacuum will immediately pass fromvacuum connection H2, open valve 58, to

`the brake control lines |33 to chamber |34 and the brakes willinstantly and automatically be applied by the air pressure in thechambers |55. The trailer brakes being thus applied constitute a safetymeasure automatically operable when the connection to the tractor brakesystem fails.

When the trailer brakes are to be applied by the driver, he steps on thebrake pedal I4 and through the relay 9| and the pneumatic brake valve l5suction is applied to the upper chamber in the relay valve T8. Thediaphragm H5 is drawn upwards and the upper plate valve 88 is opened asexplained above. Vacuum is then applied tc the brakes through the pipelines ||2 and |58 and the brakes are applied. When the pressure isremoved from the foot pedal I4, air enters the chamber from thepneumatic brake valve l5 and vacuum supplied through pipe line ||2causes the diaphragm H8 to be moved inwardly so that the lower valve B5is opened. Air then enters the brake chamber and the system is againbalanced because air pressure below the diaphragm H8 will cause thelifting of the Valve stem iH5 whereby the lower plate valve 55 willagain be closed.

Since the diaphragm il can be made much larger than the diaphragm H8, asmaller pressure change in the system acting upon the diaphragm ||0 willcause a much larger and speedier change in brake pressure and a muchfaster application of the brakes results from this construction.

A temperature control valve is illustrated in Fig. 9. It is included inthe disclosure because it is an adaptation of the principles underlyingthe operation of the pneumatic brake valve except that the actuatingelement responds to changes in temperature instead of responding tochanges in pressures. The valve comprises a valve casing |55 having aninlet |5| for the hot component and an inlet |52 for the cold component,the inlets leading to a mixing chamber |53 provided with two valves |54and |55 which are connected to the casing by bellows |56. The valves areadapted to be opened and closed by a thermostat |55 having an operatinghead |53. Ilihe thermostat is carried by an adjusting shaft |59. Thevalve has an outlet at |60.

As shown in the drawing, the two components will mix in equalproportions in the mixing chamber |53. If the mixture gets warmer thanthe setting of the thermostat is adjusted for, the dissimilar metals inthe thermostat will cause it to move so as to close, partly or entirely,the valve |511 against the valve seat iti and thereby diminishing orshutting ofi the warm supply and also further open the cold valve |55away from its valve seat |52 and thereby increase the cold supply. Ifthe mixture gets too cold, the operation is reversed. The valves areoperated by the head |58 of the thermostat engaging the frame members ofthe valves as shown. The setting of the thermostat is adjusted byrotating the shaft |54 by any suitable means.

No attempt has been made in this disclosure of the invention toillustrate or describe any particular details of construction of theseveral valves or units. They will of course be manufactured inaccordance with established production practice. The entire brakingsystem disclosed is characterized by non-complicated structuresfunctioning to provide a novel, efficient, speedy and safe brakingsystem. The invention is not limited to the exact embodiments disclosed.It is to be understood that changes may be made within the principles ofthe invention and the .scope of theV appended claim.

I claim:

In a braking system of the character described, an air suspended vacuumoperated brake; a pneumatic relay valve for exhausting the atmosphericair from said brake to apply the same comprising a valve casing providedwith five chambers; a exible diaphragm placed between the rst and asecond chamber; said rst chamber being the uppermost chamber; a secondflexible diaphragm placed between said second and the third chamberbelow said second chamber; a xed partition in said valve below saidthird chamber; a trailer vacuum tank; pipes connecting said thirdchamber with said trailer vacuum tank and with said brake; an air inletto said third chamber; valve elements in said third chamber controllingthe passage of vacuum and air to the said brake to apply and release thesame; a valve stem in said valve connecting the said two diaphragms withsaid valve element to operate the latter; a, pneumatic brake valve; apipe connecting the latter with the said rst chamber in the pneumaticrelay valve for supplying vacuum thereto to flex the said firstdiaphragm to actuate the said valve stem and valve elements; a tractorvacuum tank; a third flexible diaphragm placed below said Iixedpartition and providing said pneumatic relay valve with two chambersbelow the partition; a pipe connecting the chamber below the lastmentioned diaphragm with both of said vacuum tanks; a valve rod restingupon the last named diaphragm and extending upwards to engage ReferencesCited in the le of this patent UNITED STATES PATENTS Number Name Date1,569,143 Robinson Jan. 12, 1926 2,150,021 Christensen Mar. 7, 19392,161,279 Bowen June 6, 1939 2,215,172 Christensen Sept. 1'7, 19402,228,631 Kuiper Jan. 14, 1941 2,230,048 Elliott Jan. 28, 1941 2,266,264Reed Dec. 16, 1941 2,279,276 Oliver Apr. 7, 1942 2,304,621 Baade et alDec. 8, 1942 2,349,051 Novak May 16, 1944 2,374,855 Fitch May 1, 19452,385,625 Hopmans Sept. 25, 1945 2,442,057 Page May 25, 1948 2,498,108Gunderson Feb. 21, 1950 2,537,535 Larsson Jan. 9, 1951 2,544,849 MartinMar. 13, 1951 FOREIGN PATENTS Number Country Date 564,097 Great BritainSept. 13, 1944

